Well, he’s managed to smelt very small amounts of iron out of mud. So in theory he could get himself as far as the iron age on his own. Eventually he’ll hit limits based on lack of trade; he can make iron from mud and lime from snail shells, but eventually I assume he’ll hit something he can’t get locally. Local historical steel quality was affected by clay, iron ore etc., so he might not have the right stuff to make crucible steel, regardless of how much mud he fires.
Of course, if civilization falls, getting to this information while it’s still useful could be tricky. Like, will the apocalypse happen slowly enough to print off the relevant wikipedia pages? Does anyone make a “So you want to reboot technological civilization from first principles” text?
